Phenol-aldehyde resin composition containing pecan pith extract and an aldehyde

ABSTRACT

A phenol-aldehyde resin composition consisting essentially of the polymerization product of an alkali organic extract of peanut hulls and pecan piths polymerized with an aldehyde. The peanut hull and pecan pith alkali organic extract are polymerized with an aldehyde and used to formulate resins suitable for use in polywood adhesives, in molding compounds, in wood bonding agents and in cellulosic material impregnating agents.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to extracts from peanuts hulls and pecan pith,processes for such extraction, the use of the extract for thepreparation of phenolic-type resins, and the use of such resins inadhesives and as bonding agents for wood laminates, particle board, andthe like.

2. Description of Prior Art

For many years agricultural residues, such as tree bark, sawdust, peanuthulls, and pecan pith, were regarded as waste products to be disposed ofas cheaply as possible. However, in this era of material shortages andecological awareness, increasing efforts have been directed away frommere disposal and toward positive utilization of such residues. Althoughmost of such residues are still disposed of by burning or dumping,increasingly stringent air and water pollution regulations coupled withthe high potential value they may have as raw materials suggests thatmaximum utilization of the residues is a necessity.

The use of various tree barks, especially pine, oak and redwood, andother residues, such as oat hulls, walnut shells, wood flour, andconiferous strobiles, as extenders or fillers for phenol-aldehyde resinsis well known. It is also known to make alkali extracts of various treebarks and to use such alkali extracts in phenol-aldehyde resinproduction.

There has, however, been no disclosure of the production of alkaliextracts of peanut hulls or pecan piths or the use of such extracts as apartial or complete substitute for phenol in phenol-aldehydecondensation under alkaline conditions.

Relevant prior art of which the applicant is aware is as follows:

U.S. Pat. No. 1,078,893 relates to extracting tannin from pecan shellsand pith. The disclosed process consists of comminuting pecan shells andpith, mixing them with boiling water, and extraction by percolation.There is no disclosure of the use of an alkaline solution.

U.S. Pat. No. 2,574,784 relates to a phenolic resin adhesive compositioncontaining a comminuted bark extender.

U.S. Pat. No. 2,574,785 relates to a process for treating vegetableshell material for use as a constituent of phenolaldehyde adhesivecompositions. The vegetable shell materials specifically disclosed arenut shells, such as walnut, filbert and hickory, the endocarps (stones)of drupes, such as apricot, peach and prune, and the barks of trees.

U.S. Pat. No. 2,675,336 discloses a phenolic resin especially adaptedfor use in the manufacture of plywood which is the reaction produce ofphenol, alkaline redwood bark extract, and formaldehyde. The use of morethan 50% alkali soluble redwood bark extract by weight in the phenoliccomponent is disclosed as resulting in resins of substantially reducedreactivity. Wood flower, walnut shell flour, and pulverized oat hullsare disclosed as fillers.

U.S. Pat. No. 2,773,847 discloses the reaction of tree bark fractionswith an alkaline compound which is then further reacted with an aldehydeto form a resin. It is disclosed that bark fractions comprising lessthan about 68% cork prove to be unsatisfactory as the principalingredients in a causticformaldehyde bark adhesive.

U.S. Pat. No. 2,781,286 relates to phenolic resin glue compositionscontaining extenders, which are finely divided modified vegetable shellmaterials containing certain alkali derivatives. Vegetable shellmaterials disclosed are the endocarps of drupes, which include shells ofnuts, such as walnut, hickory, palm and filbert, pit shells of fruits,such as peach, prune and apricot, the hulls of grains and seeds, such asoat hulls, and the cones or strobiles of coniferous trees.

U.S. Pat. No. 2,782,241 relates to the digestion of coniferous barks inan aqueous alkaline solution so as to convert part of thewater-insoluble portion of the bark to a water-soluble alkaliderivative.

U.S. Pat. No. 2,819,295 is similar to U.S. Pat. No. 2,782,241 butrelates to a different fraction of the organic chemicals of the bark andis further characterized by retained or combined nitrogen.

U.S. Pat. No. 2,823,223 relates to an improved process for theproduction of chemical derivatives from coniferous barks by digestion inan aqueous ammonia solution.

U.S. Pat. No. 2,831,022 relates to sodium sulfonate or sulfonic acidderivatives of polymeric phenolic materials occurring in bark and theuse of such compositions as chemical intermediates and well drillingadditives.

U.S. Pat. No. 3,008,907 relates to an extender for phenolic resins whichis an alkali metal reaction product of a conjointly cooked alkalinemixture of a cereal flour and a vegetable material which may beligno-cellulose. The disclosed cereal flour is wheat flour. Thedisclosed ligno-cellulose materials are tree bark, nut shells, and theendocarps of drupes.

U.S. Pat. No. 3,017,303 relates to extenders for phenolic resinadhesives which are naturally occurring ligno-cellulose and alkalilignin.

U.S. Pat. No. 3,025,250 relates to phenolic resins which are furtherreacted with alkali-bark derivatives obtained by treating suitable barkat a temperature of from about 90° to 170° C. with an aqueous alkalinesolution.

U.S. Pat. No. 3,053,784 relates to resins derived from a sodium salt ofa polymethylol phenol and a sodium substituted bark derivative. It isone of the important aspects of this invention that free formaldehyde isneither present in nor added to the composition.

U.S. Pat. No. 3,093,605 relates to extenders for plywood adhesivesolutions composed of a vegetable shell flour extender and minor amountsof an at least partially oxidized extracted lignin and a non-fibrousdegradation product of a vegetable shell material.

U.S. Pat. No. 3,093,607 is closely related to U.S. Pat. No. 3,093,605.

U.S. Pat. No. 3,099,633 is closely related to U.S. Pat. No. 3,093,605.

U.S. Pat. No. 3,213,045 relates to phenolic resin adhesives formulatedwith redwood bark dust resin extenders.

U.S. Pat. No. 3,223,667 discloses a resin composition comprising analkali-bark derivative and a polymethylol phenolic compound which willpolymerize to a phenolic resin and will also condense with thealkali-bark derivative.

U.S. Pat. No. 3,232,897 relates to resorcinol-formaldehyde cold settingadhesive resins incorporating alkali-bark derivatives as an extender.

U.S. Pat. No. 3,268,460 relates to condensing phenol and aldehyde tomake a resinous condensate and then further condensing said resin withbark flour.

U.S. Pat. No. 3,293,200 relates to phenol resins containing, as anextender, a water-insoluble, finely-divided humin material obtained fromthe manufacture of levunic acid by acid hydrolysis of ligno-cellulose.

U.S. Pat. No. 3,328,322 relates to thermosetting molding materialscomprising a phenol-aldehyde resin and an alkali-extracted douglas firbark fiber.

U.S. Pat. No. 3,371,054 relates to alkali-bark derivatives produced bytreating bark with an alkali metal hydroxide in strong aqueous solutionwhich is heated sufficiently to carry the batch to a substantially drystate while in a non-oxidizing atmosphere, to form an alkali bark. Thealkali bark may be acidified to form an acid bark. Either the acid barkor the alkali bark may be reacted with formaldehyde to form novolak-typeor resole-type resins.

U.S. Pat. No. 3,389,101 relates to a resin adhesive for use in themanufacture of plywood which is formulated from a redwood extractcomposed of phenolics which are solvent-extracted from redwood, andphenol co-reacted with formaldehyde in the presence of an alkalihydroxide catalyst.

U.S. Pat. No. 3,429,770 relates to an extender for plywood gluecompositions.

U.S. Pat. No. 3,518,210 discloses an infusable resin formed by reactionof a phenol-aldehyde condensation product with an alkali-barkderivative.

U.S. Pat. No. 3,654,200 relates to a liquid coniferous tree bark alkaliwhich is reacted with a dimethylol amide of a dibasic acid and used as asubstitute for up to 65% of phenol-formaldehyde in adhesive resinformulae.

U.S. Pat. No. 3,931,071 relates to lignin sulfonatephenol formaldehydeglue systems for particle board, hardboard and plywood.

Japanese laid-open patent application No. 50/34054 discloses the use ofpeanut hulls as an extender in phenol-formaldehyde resin adhesives foruse in plywood manufacture.

Relevant literature includes the following.

Kottwitz and Forman, Sodium Palconate, Industrial and EngineeringChemistry, Volume 40, No. 12 (1948), pages 2443-2450. This articlediscloses the production of powdered sodium palconate by alkalineextraction of redwood bark dust followed by concentration and spraydrying of the extract. The alkali-soluble material was disclosed asconsisting mainly of a partially methylated phenolic acid containingaliphatic hydroxyls, phenolic hydroxyls, and carboxyl groups, in theratio of 2:4:3.

Kulvik, Chestnut Wood Tannin Extract in Plywood Adhesives, AdhesivesAge, March (1976), pages 19-21. This discloses a phenol-formaldehyeresin in which up to 50% of the phenol is replaced by a chestnut woodtannin extract added prior to the reaction with formaldehyde.

Kulvik, Chestnut, Tannin Extract as Cure Accelerator forPhenol-Formaldehyde Wood Adhesives, Adhesives Age, March (1977), pages33-34. Chestnut wood tannin extract is disclosed as replacing resorcinoland/or paraformaldehyde as an accelerator for the cure of alkalinephenol-formaldehyde adhesive resins and has an accelerating effect onthe cure of phenolic adhesives for plywood manufacture.

Saayman and Brown, Wattle-Base Tannin--Starch Adhesives for CorrugatedContainers, Forest Products Journal, Volume 27, No. 4, April (1977),pages 21-25. Polyphenolic bark tannin is disclosed as a substitute forresorcinol in the production of moisture-resistant corrugated board. Thebark tannins of the wattle tree are stated to resemble resorcinol moreclosely than phenol.

Herrick and Bock, Thermosetting Exterior-Plywood Type Adhesives fromBark Extracts, Forest Products Journal, Volume 8, No. 10 (1958), pages269-274.

McLean and Gardner, Bark Extracts in Adhesives, Pulp and Paper Magazineof Canada, Volume 53, August (1952), pages 111-114.

Abe, Studies on the Lignin-Formaldehyde Resin, Hokkaido Forest ProductsResearch Institute Research Report No. 55, (1970), pages 1-131.

Hall, Leonard and Nicholls, Bonding Particle Board With Bark Extracts,Forest Products Journal, Volume 10, No. 5, (1960), pages 263-272.

Chen and Rice, Veneer and Assembly Condition Effects on Bond Quality inSouthern Pine Plywood, Forest Products Journal, Volume 23, No. 10,(1973), pages 46-49.

In addition to the above, the inventor presented a paper at thethirtieth annual meeting of the Forest Products Research Society held inToronto, Canada, on July 13, 1976, entitled "Studies On The Use of Barkand Agricultural Residue Components In Phenolic Resins and GlueMixes--Part I--Relative Activity Of Bark and Residue Extractives TowardFormaldehyde". This paper disclosed the extraction of phenol-likecompounds from southern pine bark, oak bark, pecan nut pith, and peanuthulls. Various extraction means were disclosed including aqueous sodiumhydroxide extraction, sulfite pulping method extraction, and hydrolysisby means of the "Hokkaido Process" to produce lignin-like compounds.Some, but not all, of the extracted components reacted rigorously withformaldehyde.

SUMMARY OF THE INVENTION

It has been discovered that a substance can be isolated from twoagricultural residues, namely peanut hulls and pecan piths, which may bereacted with aldehydes under alkaline conditions so as to formphenol-aldehyde type A and type B resins, which then may be used eitheralone or in admixture with other ingredients as adhesives or bondingagents, which are heat cured to type C resins. The process of extractionof the useful compounds from the peanut hulls or pecan piths isextremely important. The preferred extraction is by reaction of thepeanut hulls or pecan piths residues with an alkali in an aqueous systemat a temperature of from about 20° to about 400° C., under atmosphericor in elevated pressure, and for a time sufficient to react the residuewith the alkali, thus producing an alkaline extract solution and/orsuspension. The alkaline extract is then treated to remove non-suspendedparticles, after which the extract is concentrated to from 2 to 100% byweight of solids by water removal, using any conventional means. Thealkaline concentrate thus produced is believed to contain variousphenols and polyphenols, as well as cellulose derivatives and lignincompounds. This residue extract has been found to be an extremely usefulreactant material for the production of alkaline phenolaldehyde resins.

Various types of resin polymers, copolymers and heteropolymers may beproduced, depending upon the polymerization method. Some of these resinsare as follows.

Resin I

The residue extract may be reacted directly with an aldehyde to form athermosetting resin.

Resin III

A conventional type B phenol-aldehyde resin (Resin II) may be simplymixed with Resin I (when still at type B stage), and the mixture may beheat cured.

Resin III-A

Resin I and Resin II may be mixed while they are still in theprecondensate stage, that is, while they are still type A or early stagetype B resins, and then further reacted prior to curing with theaddition of further aldehyde if necessary to produce a resin copolymer.

Resin IV

Up to 80% of the residue extract may be substituted by phenol and themixture then reacted with an aldehyde under conventional conditions toproduce a resin copolymer.

Resin V

A precondensate (type A or early stage type B) of Resin II may befurther reacted with the residue extract to produce a copolymer.

The resins thus produced may be used as adhesives for the manufacture ofplywood, wood veneers, or similar laminates, as well as for bondingparticle board, fiber board, strip board, and similar manufacturedcellulosic products. The resins may be used either as is, or with theaddition of extenders, fillers, gums, etc. The bonding qualities of theadhesives and the resins were found to be greatly improved over those ofconventional phenolaldehyde type resins, in that the heat curing timewas significantly shorter and the bond was at least as strong anddurable, if not better.

DETAILED DESCRIPTION OF THE INVENTION 1. Description of the RawMaterials

Peanut hulls are the preferred agricultural residue used in thisinvention. The peanut hulls may be processed without any furtherpreparation. However, in order to minimize the amount of extractedmaterials, it is generally desirable to break up the peanut hulls intopieces not larger than about 1/8 inch (0.3 cm) in diameter. The peanuthulls may be reduced to particles of this size by any conventionalmeans, such as using a hammer mill, roller mill, ball mill, etc. Thepeanut hulls also may be ground into a fine powder or flour, althoughthis does not appear to increase appreciably the amount of extractedmaterial. Peanut hulls obtained commercially may also contain minoramounts of inner skin and nut.

Pecan pith is the other agricultural residue useful in this invention.As defined herein, pecan pith means all parts of the pecan other thanthe kernel (nut) and outer shell. Pecan pith is obtained commercially asa coarse ground powder, and may contain minor amounts of kernel andouter shell.

2. Extraction of Useful Materials

(A) Sulfite Pulping Method

One means of extracting compounds from peanut hulls and pecan pithuseful in this invention is by solubilizing the compounds using sodiumsulfite and then removing the waste insolubles.

As one example of such a treatment, the raw materials were digested witha liquor that was composed of 12.3% sodium sulfite and 3.0% sodiumbisulfite for six and one-half hours after reaching a maximumtemperature of 135° C. The solids to liquid weight ratio was 1:6. Afterdigesting, the products were vacuum filtered through Whatman No. 4filter paper. The filtrates were then evaporated to a non-volatilecontent of more than 22% by a flash evaporator.

As another example of such a treatment, the same process as above wasrepeated except that the liquor had a composition of 3.9% sodium sulfiteand 1.0% sodium carbonate. The maximum temperature during the digestionprocess was 170° C.

Generally, the extractions are conducted in aqueous solutions containingfrom 3 to 15% sodium sulfite and at least one of the group consisting offrom 2 to 5% sodium bisulfite and from 0.5 to 2% sodium carbonate attemperatures of from about 100° to 200° C., until at least 2%,preferably from about 5 to about 15%, by weight of crude protein iscontained in the extract, based upon 100% by weight of total reactedorganic compounds.

(B) Alkaline Extraction Method

As a preferred method of extracting useful compounds from peanut hullsand pecan pith, the agricultural residue may be reacted with an alkaliin a solvent system, so as to make the desired compounds soluble in thatsystem. Any alkali which will react with these compounds may be used insuch a process. However, sodium hydroxide, potassium hydroxide, andammonium hydroxide are preferred, with sodium hydroxide being mostpreferred. Any type of organic or inorganic solvent can be used,provided that it can dissolve the alkali salt that is formed. However,as a practical matter, an aqueous system is most preferred.

The extraction process can be performed in one stage, or as many asthree stages, with a two-stage extraction process being preferred. Theextraction process can be conducted at room temperature by immersion ofthe residue in the alkali medium for a sufficient length of time,usually from 24 to 72 hours.

Where the extraction is to be conducted in one stage, the speed ofextraction can be increased noticeably simply by increasing thetemperature and/or alkalinity of the aqueous alkaline medium. For thispurpose, temperatures of from 20° to about 400° C., preferably from 20°to about 300° C., and most preferably from about 40° to about 100° C.,may be used. Normally, the extraction may be conducted under atmosphericpressure. However, if desired, the extraction process may be furtherspeeded up by sealing the container or by increasing the pressure, whichin effect "pressure cooks" the residues. When the extraction isconducted in one stage, the solid:liquid ratio should be from 1:4 to1:30, preferably from 1:10 to 1:20. The alkali concentration in weightpercent may be from 5 to 50% for ammonium hydroxide and from 1 to 30%for sodium hydroxide or potassium hydroxide. Preferable concentrationsare from 2 to 20 weight percent, and most preferable are from 2 to 10weight percent for sodium and potassium hydroxide, and from 7.5 to 30weight percent for ammonium hydroxide.

A multistage extraction process is also possible, with a three-stageprocess being preferred and a two-stage process being most preferred. Ina multistage extraction process, the process of the one-stage extractionis simply repeated until all useful materials are removed. Generally,the solids:liquids weight ratio is decreased for each additional stage.The solids:liquids weight ratio for the first stage should be from 1:2to 1:15, with ratios of 1:5 to 1:10 being preferred. The solid:liquidratio for the second stage can be the same, but it is also possible toreduce the liquids up to fifty percent, with the proviso that the totalsolid:liquid ratio for both stages added cumulatively is at least 1:5.It is also possible to reduce the solids:liquids weight ratio for thefirst stage with the same proviso applying.

It has been found that a three-stage extraction process does afford someadditional yield, but this is generally not sufficient to warrant theincreased expenditure of energy. Therefore, a two-stage process ispreferred.

When the extract is used per se as a bonding agent for wood particles,it generally is desirable to remove any residue remains which are notsuspended in the extract. These residue remains may be removed by anyconventional process, such as screening, filtering, or simply decantingthe supernatant liquid containing the solubilized extract and fineparticles in suspension. The primary reason for removing such residueremains is because, in the production of particle board, strand board,and the like, the bonding agent is sprayed onto the particles and thepresence of residue tends to clog the sprayer nozzle. Where the resin isapplied by other means, removal of the residue remains may not benecessary. Where the resin is used as an adhesive ingredient for woodlamination, removal of the residue remains is not necessary, and infact, the residue remains may constitute part of the fillerconventionally used in such adhesives.

The extraction process, regardless of the method used, is to continueuntil at least 2%, preferably 5 to 15%, by weight of crude protein,based upon 100 weight percent of extracted organic substances, isobtained. The most convenient method for measuring the crude protein isby conventional nitrogen analysis. One of the major advantages of resinsprepared in accordance with this invention over conventional phenolicresins and over resins prepared using alkaline tree bark extracts isthat the resins of this invention thermoset significantly faster and,therefore, significantly reduce the time required to produce glued woodproducts, resulting in significant savings in energy consumption andequipment costs.

The alkaline filtrate or the alkaline extract may then be concentratedfor purposes of storage or ease of handling. The concentration may be byany conventional means in which the desired amount of water is removed.Generally, it is desired to concentrate the alkaline extract or filtrateto from 2 to 100%, preferably from 40 to 60%, by weight of solids. Italso may be desirable to remove substantially all of the water by atechnique such as spray drying, to produce a stable dry powder which maybe dissolved and/or suspended in water when desired. Where a resin is tobe produced from the extract in a continuous flow system, it isgenerally preferable to concentrate the alkaline extract or filtrate tofrom 30 to 70% by weight of solids and use the concentrate directly inthe next step of the production process.

3. Preparation of Resins

The extracts have been found to be useful as a partial or totalsubstitute for phenol in conventional phenol-aldehyde polymerizationunder alkali conditions. Such polymerization will produce athermosetting resin which can be used as a molding compound, adhesive,bonding agent, or ingredient of molding compounds, adhesives, or bondingagents, and the like.

Phenol-aldehyde resins were one of the first thermosetting resinsproduced commercially. These resins generally can be divided into threedistinct stages in the condensation reaction of phenol with aldehyde inalkaline solution. The initial product, type A, is a liquid or semisolidand is converted by continued heating into an intermediate, type B, arelatively insoluble fusible solid. This, when subjected to heat andpressure, is converted (cured) into type C, an insoluble and infusibleresin. In the general process of manufacture of plywood, wood veneers,laminates, strip board, and particle board, a type B resin is used andis converted to a type C resin under the influence of heat and pressurewhen the finished product is produced. Acid, as opposed to alkaline,conditions generally result in production of a noncurable type of resincommonly known as a novolak, with accompanying consumption of a highpercentage of phenol. In an alkali medium, more aldehyde is utilized,even though an excess of phenol is employed, and the product is not ofthe novolak type. However, if the phenol is replaced by a substitutedphenol containing only one free active position, for example2,4-xylenol, only a noncurable novolak resin can be obtained. If thephenol has two free active positions, for example ortho- or para-cresol,partially or slowly curable resins are obtained. Thus, it is generallybelieved that two or three reactive positions must be available forformation of truly thermosetting resins. Since thermosetting resins aredesired in the subject application, any phenol which has at least two,preferably three, reactive positions will be suitable.

Commercially, the mole ratio of formaldehyde to phenol is usually1.5-3:1. It is believed that type A resins are similar in structure tonovolaks, but more highly substituted. Such a multifunctional chainpolymer would readily undergo condensation to a three dimensionalstructure. This accounts for the physical characteristics of type Cresins, which are completely insoluble in all conventional solvents.

The phenols which may be replaced entirely or in part by the extractconcentrate include all those will normally are suitable for a reactionwith an aldehyde to form a phenol-aldehyde type resin. These includegenerally alkyl phenols, polynuclear phenols, alkylene-bridge-linkedphenols, fused phenols, hydroquinones, cresols, naphthols, resorcinols,xylenols, bisphenols, and more specifically, phenol, naphthol, cresol,resorcinol, xylenol, C₁₋₅ alkyl phenols, halophenols, nitrophenols,cyclophenols, and the like. The preferred phenols used inphenol-aldehyde condensations for which the alkaline concentrate can besubstituted or which can be replaced by the alkaline concentrate arephenol, cresol, xylenol, cresylic acid, resorcinol, naphthol, C₁₋₅ alkylphenols, polynuclear phenols, fused phenols, bisphenol, halophenols, andnitrophenols. Most preferred are phenol, cresol, xylenol, andresorcinol.

The aldehydes with which the alkaline concentrate and the variousphenols may be reacted include all those which are suitable for reactionwith phenols to form phenol-aldehyde resins, including formaldehyde,acetaldehyde, butyraldehyde, heptaldehyde, furfuraldehyde,chloraldehyde, alpha-ethyl-beta-propylacrolein, benzaldehyde, glyoxal,pyruvaldehyde, cinnamaldehyde, pyrocatechualdehyde, and the like.Preferred aldehydes are formaldehyde and the formaldehyde polymers whichare capable of decomposing to furnish formaldehyde. These includeformaldehyde, paraformaldehyde, trioxane, hexamethylene tetramine,furfuraldehyde, and formalin.

RESIN I is designated herein as that resin produced by completesubstitution of the extract for phenol in the production of aphenol-aldehyde resin under alkaline conditions. One part by weight ofsolids of the alkaline concentrate is reacted with from 0.1 to 1.6 partsby weight of solids, preferably from 0.2 to 1.0 parts by weight ofsolids, of an aldehyde in an aqueous alkaline system at a temperature offrom 30° C. to reflux, until a viscosity of from 250 to 1500 cps at 25°C. is reached, to form a resin. In one embodiment of this invention, thecondensation reaction may be conducted in one step at a preferredtemperature of from about 60° to about 90° C. In another embodiment ofthis invention, the condensation reaction may be conducted at atemperature of from about 30° to about 75° C. (preferably 50° to 70° C.)until addition is completed, and then conducted at a temperature of fromabout 55° C. to reflux (preferably 70° C. to reflux) until condensationis completed, to form a resole resin. When the resin is to be used forwood laminate adhesion, it is preferred that condensation be conducteduntil a viscosity of from 300 to 1,500, preferably from about 450 toabout 800, cps at 25° C. is obtained. Where the resin is to be used as abonding agent for particle or strand board, it is preferred thatcondensation be conducted until a viscosity of from 250 to 800,preferably from about 300 to about 400, cps at 25° C. is obtained.

Because the extract is already sufficiently alkaline, it usually can bereacted directly with the aldehyde without the need for addingadditional alkaline catalyst, at the above temperatures and under normalpressure, although it is possible to adjust the alkaline concentrationto from 2 to 20, preferably 3 to 15, percent by weight.

RESIN II is used herein to designate a conventional phenol-aldehyde(formaldehyde) resin, in which there is no substitution for the phenolby the extracts of this invention, except as specifically indicated.

Unless stated otherwise, the condensation conditions for Resin I alsoapply to Resins III, III-A, IV and V, although a final viscosity of from20 to 1,500, especially 20 to 500, cps at 25° C. is desirable where theresin is to be used for the impregnation of cellulosic materials, suchas paper, canvas and wood pulp.

RESIN III is a physical mixture of 1.0 part by weight of RESIN I (typeB) and up to 4.0 parts by weight of RESIN II (type B) which mixture isthen applied as a bonding agent or used in a laminate adhesive, and heatcured.

RESIN III-A is a physical mixture of 1.0 part by weight of RESIN I (typeA or early type B) and up to 4.0 parts by weight of RESIN II (type A orearly type B), with additional aldehyde optionally added if necessaryfor polymerization to a desired viscosity, which is then, after thoroughmixing, heated together at from 55° C. to reflux so as to form athermosetting type B copolymer, useful as an adhesive ingredient and asa bonding agent.

RESIN IV is one similar to RESIN I but in which up to 80%, preferably upto 60%, more preferably up to 40%, of the extract is replaced by aphenol, preferably having at least two free active sites, and themixture then reacted with an aldehyde under conventional alkalineconditions, to produce a type B resin copolymer. Depending upon theamount of replacement of the alkaline concentrate, additional alkalishould be added so that the total amount of alkali during thecondensation process is from about 2 to about 20% by weight.

RESIN V is a phenol-aldehyde type resin, consisting essentially of thereaction product of from up to about 4.0 parts by weight of aconventional thermosetting phenol-aldehyde resin which is a RESIN IIprecondensate (type A or early type B) having a viscosity of from about20 to about 800 cps at 25° C. and about 1.0 part by weight of the solidsof the alkaline or sulfite extract. The reaction results in furtherpolymerization can best be conducted in an aqueous alkaline system inwhich the alkali concentration is adjusted to from about 2 to about 20%,preferably 3 to 15%, by weight, and at a temperature of from 30° C. toreflux, until a viscosity of from 20 to 3,000 cps at 25° C. is reached.Additional alkali may be added to adjust the concentration to thedesired value, depending upon the type and amount of extract that isused. Additional aldehyde also may be added to produce a desired polymerviscosity.

EXAMPLE 1 Two-Stage Alkaline Extraction

160 g (calculated as bone dry) of peanut hull having a particle size ofless than 0.3 cm was charged to a 2,000 cc Erlenmeyer flask. Then 1,600g of 5% NaOH aqueous solution was added. The ingredients were mixed wellby shaking the flask. The flask was then placed in a gravity convectionoven and heated at a temperature of 90°-95° C. for about 17 hours. Thecontents of the flask were vacuum filtered using Whatman #4 filterpaper, to remove non-suspended solid particle residue. The filtrate wasput aside and stored at room temperature. The residue was subjected to asecond extraction using the same equipment, by the addition of 1,280 gof fresh 5% NaOH aqueous solution and again heated in the convectionoven at 90°-95° C. for about 17 hours. The filtration process wasrepeated and the two filtrates were mixed. The filtrate residue wasdried and reserved. The filtrate was concentrated by placing it in anopen beaker in a forced air oven maintained at 90°-95° C. for severaldays until a solids concentration of about 40% by weight was reached.

The above process was repeated several times, and the alkaline extractswere mixed together, until a sufficient amount was prepared to conductvarious resin syntheses.

EXAMPLES 2-11 Additional Two-Stage Alkaline Extractions

Additional extractions were conducted varying the alkalineconcentration, the temperature, and the raw material from which theextract was to be derived. The alkaline solution: raw material ratio was10:1 for the first step and 8:1 for the second step, as follows.

                  TABLE I                                                         ______________________________________                                                                        Alkaline                                                           Temperature                                                                              Concentration                                 Example No.                                                                            Raw Material                                                                              (° C.)                                                                            (%)                                           ______________________________________                                        2        peanut hull 40         2                                             3        peanut hull 40         10                                            4        peanut hull 95         2                                             5        peanut hull 95         10                                            6        pecan pith  40         2                                             7        pecan pith  40         5                                             8        pecan pith  40         10                                            9        pecan pith  95         2                                             10       pecan pith  95         10                                            11       peanut hull 95         5, 10*                                        ______________________________________                                         *In this particular example, the first stage was at a 5% concentration an     the second was at a 10% concentration.                                   

EXAMPLE 12 Three-Stage Alkaline Extraction

Example 1 was repeated except that the NaOH concentration was 2% and thefiltrate residue was subjected to a third extraction stage using thesame equipment, by the addition of 960 g of fresh 2% NaOH aqueoussolution and again heated in the convection oven at 90°-95° C. for about17 hours followed by filtration. The filtrates from the three steps weremixed together.

EXAMPLE 13 Extraction by Neutral Sulfite Pulping Method

An extract was prepared using a sealed pressure vessel equipped with astirrer, a thermocouple, a cooling coil and a pressure gauge, and havinga capacity of about 1,200 cc. This vessel was charged with 100 g(calculated as bone dry) of peanut hull reduced to 0.3 cm or lessparticle size, and 600 g of an aqueous solution containing 3.9% byweight of sodium sulfite and 1.0% by weight of sodium carbonate. Thevessel was heated to about 170° C. with constant stirring, andmaintained at the temperature for 6 hours. The vessel was then cooled soas to stop the extraction process. The contents were then vacuumfiltered through Whatman #4 filter paper, and the extract residue setaside. The filtrate was then concentrated with a flash evaporator atabout 60° C. until a solids concentration of about 30% by weight wasreached.

EXAMPLE 14 Extraction by Neutral Sulfite Pulping Method

The process of Example 12 was repeated, using pecan pith instead ofpeanut hulls.

ANALYSIS OF EXTRACT COMPONENTS

Extracts of various raw materials, both within and outside the scope ofthe subject invention, were analyzed as follows.

The ash content was obtained after heating a sample of the extract at600° C. for 2 hours. The analysis of the other components was asfollows:

(a) Nitrogen analysis was conducted on a portion of the extract.

(b) The extract was neutralized with HCl (pH of 3).

(c) The neutralized product was vacuum evaporated (less than 10 mm Hg,2-3 hours).

(d) Volatile matter was not analyzed.

(e) Ether extraction was conducted on a portion of the evaporatedresidue (reflux, 10 hours). This extract was evaporated so as to performan analysis of crude fat.

(f) The extract residue obtained in (e) was further extracted withchloroform, and the chloroform extract was analyzed. As a result,aromatic, carboxylic, and methyl moieties were found. The residue of thechloroform extract was further extracted with ethanol and the ethanolextract was analyzed. An analysis showed the presence of phenolic andcarboxylic acid moieties. The residue after ethanol extraction was notanalyzed.

(g) A portion of the neutralized product of step (a) was boiled insulfuric acid (reflux, 30 minutes), then boiled in NaOH (reflux, 30minutes), and then was filtered. The filtrate was not analyzed, but theresidue was analyzed for cellulose and organic matter.

The results of the above analyses are as follows:

                                      TABLE II                                    __________________________________________________________________________    Extract Analyses As Percentage Of Total Solids                                         Peanut                                                                              Peanut Pecan  Redwood                                                                             Redwood                                                                              So. Pine                                                                            So. Pine                               Hulls Hulls  Pith   Bark  Bark   Bark  Bark                                   5% NaOH,                                                                            10% NaOH,                                                                            10% NaOH,                                                                            5% NaOH,                                                                            10% NaOH,                                                                            5% NaOH,                                                                            10% NaOH,                     Component                                                                              95° C.                                                                       95° C.                                                                        95° C.                                                                        95° C.                                                                       95° C.                                                                        95° C.                                                                       95° C.                 __________________________________________________________________________    Sodium   44.0  47.6   27.9   26.3  25.6   29.0  20.1                          Ash      91.9  93.7   66.6   62.4  79.7   72.0  77.0                          Nitrogen 0.4   0.34   0.5    0.07  .055   0.13  .05                           Crude Protein                                                                 (Nitrogen × 6.25)                                                                2.4   2.1    2.9    0.4   .34    0.8   .31                           Crude Fat                                                                     (Ether Extract)                                                                        0.7   0.3    0.5    3.1   --     7.6   --                            Crude Fiber                                                                            0.1   0.1    0.5    >0.1  --     >0.1  --                            Lignin   >0.1  >0.1   >0.1   >0.1  --     >0.1  --                            Silica   1.1   >0.1   >0.1   >0.1  --     >0.1  --                            Chloroform                                                                    Extract* 0.7   0.4    0.3    0.4   --     2.3   --                            Ethanol Extract                                                                        4.2   10.5   5.7    26.2  --     24.8  --                            __________________________________________________________________________     *aromatic, carboxylic, and methyl moieties were identified               

An analysis of the crude protein as a percentage of the total organicsextracted is as follows:

                  TABLE III                                                       ______________________________________                                                               Crude Protein As                                                              Percentage Of                                          Extract (Example)      Organics Extracted                                     ______________________________________                                        Peanut Hull - 5% NaOH, 95° C. (Ex. 1)                                                         10.2                                                   Peanut Hull - 10% NaOH, 95° C. (Ex. 5)                                                        12.2                                                   Pecan Pitch - 10% NaOH, 95° C. (Ex. 10)                                                       5.6                                                    Southern Pine Bark - 5% NaOH, 95° C.                                                          1.6                                                    Southern Pine Bark - 10% NaOH, 95° C.                                                         0.5                                                    Redwood Bark - 5% NaOH, 95° C.                                                                0.7                                                    Redwood Bark - 10% NaOH, 95° C.                                                               0.6                                                    ______________________________________                                    

A comparison of the analytical data for the various extracts indicatesthat the only significant difference is in crude protein. It is believedthat the presence of larger amounts of crude protein in peanut hull andpecan pith than in southern pine or redwood bark is at least partiallyresponsible for the improved resins produced according to the subjectinvention. It is entirely possible that the protein acts as a catalystto increase cross-linking of the phenolic copolymer, which would explainthe shortened press time that can be achieved with the subjectinvention. This explanation, however, is only theoretical.

EXAMPLE 15 Preparation of Resin I for Use in Plywood

A 5,000 cc glass resin reaction kettle (manufactured by S.G.A.Scientific Co., Bloomfield, N.J., USA) equipped with a thermometer,internal cooling coil, stirrer, and reflux condenser was used. To thisreaction kettle was charged: an extract which was a mixture of 400 g ofthe extract of Example 1 (having 50.55% solids) and 3,432 g of theextract of Example 4 (having 34.53% solids), and which had beenpartially concentrated by the removal of excess water; and 568 g of 95%paraformaldehyde; with continual stirring. While maintaining thestirring throughout the condensation reaction, the temperature of thekettle was raised to 60°±5° C. and maintained for 90 minutes. Thetemperature was then raised to from 80° C. to reflux with continualstirring, until the viscosity reached 110 cps at 25° C. as measured by aBrookfield Viscometer, using a No. 2 spindle at 30 rpm with a factor of10. A typical adhesive formula, as disclosed herein, was then preparedand the adhesive was used in the manufacture of plywood panels in themanner described herein.

EXAMPLE 16 Preparation of Resin III-A for Use in Plywood

A Resin I precondensate was prepared using the same reaction kettle asin Example 15. To this kettle were charged 2,252 g of the extract ofExample 11 (having 58.8% solids); 578 g of 95% paraformaldehyde; and1,170 g of water; with continual stirring. While maintaining thestirring throughout the condensation reaction, the temperature of thekettle was raised to 60°±5° C. and maintained for 90 minutes. Thisformed a Resin I precondensate. The reaction was discontinued at thispoint and the Resin I precondensate set aside.

A Resin II precondensate was prepared using the same glass reactionkettle, which was charged with 1,545 g of 90% phenol (Dow ChemicalCompany); 888 g of 95% paraformaldehyde; 2,349 g of water; and 119 g of50% NaOH; with continual stirring. While maintaining the stirringthroughout the condensation reaction, the temperature was raised to60°±5° C. and maintained for 90 minutes, to form a Resin IIprecondensate, which was set aside without any further condensation.

In order to make a Resin III-A type copolymer, 1,487 g of the Resin Iprecondensate prepared above (40% extract) and 2,600 g of the Resin IIprecondensate prepared above (60% phenol) were charged to the 5,000 ccglass resin reaction kettle used above and thoroughly mixed. Thetemperature was then raised to from 80° C. to reflux with continualstirring, until the viscosity reached 338 cps at 25° C. as measured by aBrookfield Viscometer using a No. 2 spindle at 30 rpm, with a factor of10. The copolymer so produced was suitable for use in an adhesiveformulation for plywood. Based upon test results using this resin, it isbelieved preferable that the final condensation reaction be continueduntil a viscosity of at least 450 ±50 cps is reached.

EXAMPLE 17 Preparation of Resin IV for Use in Plywood

The same glass resin reaction kettle as used in the previous exampleswas used. To this reaction kettle was charged 2,087 g of the extract ofExample 1 (42.8% solids, 60% extract) and 661 g of 90% phenol (40%phenol); 799 g of 95% paraformaldehyde; and 1,253 g of water; withcontinual stirring. While maintaining the stirring throughout thecondensation reaction, the temperature of the kettle was raised to60°±5° C. and maintained for 90 minutes. The temperature was then raisedto from 80° C. to reflux, with continual stirring, until the viscosityreached 450±50 cps at 25° C. as measured by a Brookfield Viscometer,using a No. 2 spindle at 30 rpm, with a factor of 10. This resin wasthen used in the standard formula given below to prepare an adhesivemixture suitable for plywood manufacture.

EXAMPLE 18 Preparation of Resin IV for Use in Particle Board

A resin was prepared in the same manner as Example 17 except using 2,858g of the extract of Example 1, (37.5% solids, 60% extract); 793 g of 90%phenol (40% phenol); 1,079 g of 95% paraformaldehyde; and 521 g ofwater. The reaction was continued until a final viscosity of about 350cps was reached. This resin was suitable for use as a bonding agent inparticle board without further preparation. The resin had a highersolids content and a lower water content than those resins to be usedfor plywood manufacture, because this is generally preferred for themanufacture of particle board.

EXAMPLES 19-33

Additional resins were prepared in accordance with Example 17 when foruse in plywood and Example 18 when for use in strand (particle) board,except using the following extracts, substituted for phenol, in thefollowing percentages. As shown in Tables IV and V below, the resincompositions can contain 80 to 20% extract and 20 to 80% phenol. Theresins for use in plywood manufacture were prepared as adhesives usingthe formula disclosed herein.

                  TABLE IV                                                        ______________________________________                                        Examples 19-30 - Preparation of Resins for Plywood                                        Extract Used  Phenol                                              Resin Example                                                                             (Example)     Replacement (%)                                     ______________________________________                                        19          2             40                                                  20          3             40                                                  21          4             40                                                  22          5             40                                                  23          6             40                                                  24          7             60                                                  25          8             40                                                  26          9             40                                                  27          10            40                                                  28          12            40                                                  29          13            20                                                  30          14            40                                                  ______________________________________                                    

                  TABLE V                                                         ______________________________________                                        Examples 31-33 - Preparation of Resins                                        for Particle Board                                                                        Extract Used  Phenol                                              Resin Example                                                                             (Example)     Replacement (%)                                     ______________________________________                                        31          1             80                                                  32          5             40                                                  33          8             40                                                  ______________________________________                                    

EXAMPLE 34 Preparation of Resin V for Use in Plywood

A Resin II precondensate was first prepared using the same glass resinreaction kettle as in the previous examples. Under continual stirring,963 g of 90% phenol, 805 g of paraformaldehyde, 1,724 g of water and 74g of 50% NaOH were charged and a precondensate was formed by raising thetemperature of the kettle to 60°±5° C. for 90 minutes, under continualstirring. The heating was interrupted at this point and 983 g of theextract of Example 11 (58.8% solids) and 251 g of water were added, withcontinual stirring. The heating was then resumed under continualstirring and the temperature was raised to from 80° C. to reflux, untilthe viscosity reached about 400 cps at 25° C. as measured by aBrookfield Viscometer, using a No. 2 spindle at 30 rpm with a factor of10. The resin so produced was used in the disclosed adhesive formula andwas found suitable for the manufacture of plywood.

COMPARATIVE EXAMPLE C-1

A two-stage alkaline extract was prepared according to Example 1, exceptthat the raw material was coarsely ground redwood bark, the alkalinesolution was a 5% concentrate, and the extraction was conducted at about95° C. This extract was then used to make a Resin IV type copolymeradhesive for plywood with a 60% replacement of phenol by the extract,similar to Example 17.

COMPARATIVE EXAMPLE C-2

A resin was prepared according to Comparative Example C-1 except thatthe alkaline concentration was 10% and that 40% of the phenol wasreplaced by the extract.

COMPARATIVE EXAMPLE C-3

A resin was prepared according to Comparative Example C-1 except thatthe raw material was coarse oak bark, the alkaline concentration was 2%,the extraction was conducted at 40° C., and 40% of the phenol wasreplaced by the extract.

COMPARATIVE EXAMPLE C-4

A resin was prepared according to Comparative Example C-3, except thatthe extraction was conducted at 95° C.

COMPARATIVE EXAMPLE C-5

A resin was prepared according to Comparative Example C-1 except thatthe raw material was coarse southern (yellow) pine bark, the alkalineconcentration was 2%, the extraction was conducted at 95° C., and 40% ofthe phenol was replaced by the extract.

COMPARATIVE EXAMPLE C-6

A resin was prepared according to Comparative Example C-5 except thatthe alkaline concentration was 10%.

COMPARATIVE EXAMPLE C-7

An adhesive was prepared according to Comparative Example C-6 exceptthat the extraction was conducted at 40° C.

COMPARATIVE EXAMPLE C-8 (Plywood Control)

As a control, plywood was manufactured in the same manner as theexamples of this invention, except using a commercially available 100%phenol-formaldehyde resin, having a solids content of 40%, a NaOHcontent of 5.4%, a viscosity of 937 cps at 25° C. measured with aBrookfield Viscometer using a No. 2 spindle at 30 rpm and a factor of10, and having 0.08% of free formaldehyde.

COMPARATIVE EXAMPLE C-9 (Strand Board Control)

As a control, strand (particle) board was manufactured in the samemanner as the examples of this invention using a commercially available100% phenol-formaldehyde resin having a solids content of 45.6%, a pH of12.1 measured on a glass electrode pH meter (mgd. by Hitachi Horiba Co.,Japan), and a viscosity of 346 cps measured on a BL Type Visco Tester,according to Japanese Industrial Standard K-6838 (1970).

COMPARATIVE EXAMPLE C-10 (Strand Board Control)

As a second control, strand (particle) board was manufactured in thesame manner as Example C-9 except using a different commerciallyavailable 100% phenol-formaldehyde resin having a solids content of36.7%, a pH of 11.4, and a viscosity of 247 cps, both values measured inthe same manner as in Example C-9.

4. Preparation of an Adhesive for Plywood Manufacture

For all of the plywood specimens manufactured for the purposes of thisinvention, the following adhesive composition was used.

    ______________________________________                                                                 Proportion                                           Ingredient and Mix Detail                                                                              By Weight                                            ______________________________________                                        Water (tap water as received)                                                                          18.0%                                                Regular grind Phenofil (1)                                                                             10.2%                                                GLU-X Wheat Flour (2)    3.9%                                                  (Mix one minute)                                                             Resin to be tested       7.7%                                                  (Mix one minute)                                                             50% NaOH solution        3.6%                                                  (Mix twenty minutes)                                                         Resin to be tested (3)   56.5%                                                 (Add slowly for smooth, lump-free mix)                                       Total Ingredients        100.0%                                               Total resin solids in mix, based on 40%                                       nonvolatile content in liquid resin                                                                    25.7%                                                ______________________________________                                         Notes:                                                                        (1) a furfural derivative which is a product of Lufkin Pecan Co., Lufkin,     Texas, U.S.A.                                                                 (2) a product of Robertson Corp., Brownstown, Indiana, U.S.A.                 (3) the resin is added in two steps, and totals 64.2% of the entire           adhesive composition.                                                    

5. Veneer Preparation and Application of Adhesive Composition

Commercial southern pine veneer of one-eighth inch (0.3 cm) thicknesswas obtained from a middle Georgia mill and cut into 12"×12" (30 cm×30cm) sheets and used to make 3-plywood panels. Prior to usage in panelproduction, the veneer was checked to assure conformance to a thicknesstolerance of ±0.005 inches (1.3 mm) from the stated value. The adhesivecomposition was applied using a roller spreader (Black Brothers Co.,Mendota, Ill., U.S.A.) and controlled within the range of 83-87 poundsper 1,000 square feet of double glue line (lb./MDGL) [equivalent toapproximately 41.6 g/1,000 cm² ]. After spreading, all panel layups werestored in a gravity convection oven at 100° F. (40° C.) for assemblytime periods of 20 and 60 minutes. No prepressing was done, but duringassembly time, the layups were stored under a slight deadload to preventedge lifting. The moisture content of the veneer was approximately 4 to7%. The 3-ply layups were then hot pressed, one panel per opening, forthe various press times, as indicated in Table VI, using a platentemperature of 300° F. (149° C.) and a panel pressure of 200 psi (about14 kg/cm²). Immediately upon removal from the hot press, the panels werestored in an insulated but unheated oven for an overnight period tosimulate hot stacking.

6. Testing of Plywood

Testing of the panels was carried out in accordance with thevacuum-pressure plywood shear method, as described in U.S. Department ofCommerce Standard PSl-74. Upon completion of the hot stacking period,the panels were brought to room temperature and cut into three 31/4"(8.26 cm) wide strips, as measured along the face grain axis. The centerstrip was held in reserve and the two outside strips each cut to yieldeight standard plywood shear specimens. The grooving of these two stripswas such that, when tested, the specimens were balanced with regard tothe effective opening and closing of lathe checks. A total of 12specimens from each panel, six selected at random from each strip groupof eight, were tested according to the vacuum-pressure procedure forexterior glue lines, as outlined in the standard. The figures for woodfailure, as shown in the following table, each represent the average of24 specimens, 12 taken from each of two duplicate panels.

The data in Table VI should be viewed by comparison with the resin ofExample C-8, which is a commercial resin used as the control. Themanufacturer of this resin recommends a minimum hot press time of 3minutes, but a hot press time of 4 minutes is generally used forcommercial production. It should be noted that many of the resins of thesubject invention achieve an acceptable result after only 2 minutes ofhot press time, as contrasted with the control resin.

                                      TABLE VI                                    __________________________________________________________________________    Plywood Shear Test Data According To PS1-74                                           Percentage of Wood Failure for Various Hot Press Times and                    Assembly Times as Indicated                                                   Hot Press - 1.5 min.                                                                    Hot Press - 2 min.                                                                          Hot Press - 3 min.                                                                        Hot Press - 4 min.                Resin Used                                                                            20 min.                                                                            60 min.                                                                            20 min.                                                                              60 min.                                                                              20 min.                                                                              60 min.                                                                            20 min.                                                                            60 min.                      (Example No.)                                                                         Assembly                                                                           Assembly                                                                           Assembly                                                                             Assembly                                                                             Assembly                                                                             Assembly                                                                           Assembly                                                                           Assembly                     __________________________________________________________________________    C-8      0    0    0     69     77     92   93   91                            15*    --   --   delaminated                                                                          delaminated                                                                          delaminated                                                                           0    5   12                           16      60   60   84     87     90     95   --   --                           17      25   69   82     85     89     90   --   --                           19      --   --   85     61     84     71   83   56                           20      --   --   88     68     89     75   85   41                           21      --   --   85     68     89     82   85   80                           22      --   --   85     76     92     90   88   78                           23      --   --   24     93     56     88   68   97                           24      0    31   79     74     65     90   --   --                           25      --   --   90     90     88     90   91   83                           26      --   --   80     88     83     90   83   87                           27      --   --   75     68     90     65   84   61                           28      --   --   --     --     --     --   91   41                           29      --   --   --     --     --     --   64   82                           30      --   --   61     76     77     78   67   67                           C-1     --   --   57     25     48     35   --   --                           C-2     --   --   56     27     62     35   --   --                           C-3     --   --   49     83     68     88   76   86                           C-4     --   --    5     81     68     80   61   82                           C-5     --   --   66     92     85     90   72   81                           C-6     --   --   74     71     90     64   91   72                           C-7     --   --   86     68     85     43   85   45                           __________________________________________________________________________     *The poor results for Example 15, which was intended to be within the         scope of this invention, are believed to be caused by insufficient            polymerization, since the viscosity achieved of about 110 cps at              25° C. was too low, and the polymerization should have continued       until a viscosity as disclosed in the detailed discussion of Resin I was      reached.                                                                 

It also should be noted that, in industrial production, the assemblytime is generally around 20 minutes. The 60-minute assembly time wasused to see whether delays in assembly could be tolerated using thevarious resins. Of interest is that, in some instances, a 60-minuteassembly time produces a lower percentage of wood failure, whichindicates that the adhesive is less successful after the time delay.This may be explained by dryout of the glue line. In Table IV, a highernumber is desirable.

The resin of Example 23 is particularly useful because of the excellentresults for 60-minute assembly times. When a highly absorbent veneer,such as southern (yellow) pine or a tropical hardwood is used, or whenassembly is in a hot atmosphere, dryout of the glue line is very common.The excellent 60-minute assembly time results of Example 23 indicatethat this resin has excellent dryout resistance. The poor result for 20minutes assembly can be improved by adjusting the resin viscosityupwards during polymerization, and adjusting the formula of the adhesivecomposition.

7. Use of Resins in Strand (Particle) Board Manufacture (for testing)

Douglas fir lumber was made into strands by a shaving machine, eachstrand having a width of 5-10 mm, a thickness of 0.3-0.5 mm, and alength of 50-75 mm. The strands were placed in a dryer and dried untiltheir moisture content became less than 3%. The strands were then placedin a blender and the resins were sprayed on the strands, giving arelatively uniform application. The strands were then placed on astainless steel plate 40 cm×40 cm so that all of the strands weresubstantially parallel and formed a first layer 30 cm×30 cm of 2 mmthickness. Then additional parallel strands were placed upon, and atright angles to, the strands of the first layer, to form a second (core)layer of 8 mm thickness. Then a third layer of parallel strands at rightangles to the core layer was placed upon the core layer at a thicknessof 2 mm. The mat thus formed was heat compressed at 180° C. and 30kg/cm² pressure, followed by cooling, using various press times asindicated in Table VII. The resins to be tested all were applied at therate of 5% of resin solids per 100% by weight of bone dry wood.

8. Testing of Strand (Particle) Board

The strength of the internal bond of the strand board was measured inaccordance with ASTM-D-1037 (64). Each of the values in Table VII is anaverage of six specimens conducted upon two pieces from each of threedifferent boards.

                                      TABLE VII                                   __________________________________________________________________________               Internal Bond Strength-                                                                   Test of Strand Board According                                                to ASTM-D-1037 (64) - Average                                                 of 6 Specimens (kg/cm.sup.2)                                                                Example 18                                                                          Example 31                         Example C-9                                                                             Example C-10                                                                           Example 33                                                                             Example 32                                                                             Press Time                                                                          Press Time                         Press Time (min.)                                                                       Press Time (min.)                                                                      Press Time (min.)                                                                      Press Time (min.)                                                                      (min.)                                                                              (min.)                             __________________________________________________________________________    2.5                                                                             3.0                                                                             3.5                                                                              4.0                                                                              2.5                                                                             3.0                                                                             3.5                                                                             4.0                                                                              2.5                                                                             3.0                                                                             4.0                                                                             5.0                                                                              2.5                                                                             3.0                                                                             4.0                                                                             5.0                                                                              3.0                                                                              4.0                                                                              3.0                                                                              4.0                             * * 0.46                                                                             2.96                                                                             * * * 2.0                                                                              * 4.3                                                                             5.7                                                                             5.3                                                                              2.8                                                                             5.6                                                                             6.5                                                                             6.2                                                                              4.1                                                                              4.5                                                                              2.2 3.1                            __________________________________________________________________________     Note:                                                                         * means delamination of board and test discontinued                      

Table VII cleary shows the superiority of the resins of the subjectinvention (Examples 18, 31, 32 and 33) over a standard commercial resin(Example C-9). The resin of Example 32, in particular, forms anacceptable bond, even after only 2.5 minutes of press time, whereas mostother resins are inoperative. After a press time of only three minutes,all of the resins of the subject invention form acceptable strand(particle) boards, whereas the board using a conventional resin (ExampleC-9) still delaminates. Furthermore, it should be noted that theinternal bond strength of a strand board formed using Example C-9 isstill inadequate even after 3.5 minutes and, in fact, requires a fullfour minutes of press time. By contrast, the resins of Examples 18, 32and 33 of the subject invention are superior after only 3 minutes, tothe resin of Example C-9 after 4 minutes, and the resin of Example 31 ofthe subject invention is also acceptable. From the above, it must bequite clear that the resins of the subject invention permit a savings ofup to 37.5% of press time, resulting in a corresponding savings ofenergy and a corresponding reduction of press capacity required forproduction. The results for the second standard commercial resin(Example C-10) are even more inferior, and indicate that there is nobonding at all until at least 4 minutes press time.

                                      TABLE VIII                                  __________________________________________________________________________    MOR (Modulus or Rupture) of Strand Board According                            to J1S A-5908, After Boiling for Two Hours in Water                           Average of 6 Specimens (kg/cm.sup.2)                                          Example C-9                                                                            Example C-10                                                                           Example 33                                                                             Example 32                                         Press Time (min.)                                                                      Press Time (min.)                                                                      Press Time (min.)                                                                      Press Time (min.)                                  __________________________________________________________________________    3.0                                                                              3.5                                                                              4.0                                                                              2.5                                                                             3.0                                                                             3.5                                                                             4.0                                                                              3.0                                                                              4.0                                                                              5.0                                                                              3.0                                                                              4.0                                                                              5.0                                          59 133                                                                              126                                                                              * * * 98 113                                                                              118                                                                              127                                                                              99 108                                                                              121                                          __________________________________________________________________________     Note:                                                                         * means delamination of board and test discontinued                      

Comparing the values in Table VIII for three minutes of press timeclearly shows the superiority of Examples 32 and 33 over ComparativeExample C-9. The values for Examples 32 and 33 may be considered asacceptable for strand (particle) board, while the value for ComparativeExample C-9 clearly is insufficient, and will result in disintegrationof the board during use. The results for the second standard commercialresin (Example C-10) and even more inferior, and indicate that there isno bonding at all until at least 4 minutes press time.

9. The Importance of Reduction of Press Time in Plywood and ParticleBoard Manufacture

On the average, processing of plywood takes about 20 minutes from thefirst application of adhesive up to the point of hot press. At thatpoint, a bottleneck in production occurs, because normal hot pressingtakes at least 3 minutes and frequently 3.5 minutes or more for a 3-plythree-eighths inch (approximately 0.95 cm) thick board, using aconventional phenolaldehyde resin. To eliminate the bottleneck wouldrequire additional hot press capacity, which would be extremely costlyand also would consume more energy. Therefore, a reduction of the timefor hot pressing will result in a substantial money and energy savings.Many of the resins of this invention can be fully cured in 2 or 2.5minutes of hot press time, thus saving from 33 to 50% of the energyexpenditure and correspondingly lower capital investment.

In the manufacture of particle board, strand board, hardboard, or anysynthesized cellulosic product of similar nature, the time savings iseven more important, because such boards are often thicker than plywoodand often require an even longer press time. Thus, the rapidthermosetting resins of the subject invention save even more time andenergy in absolute terms.

10. Use of Resins in Molding Powders

When the resins of the subject invention are used for molding, themolding powder consists of type B resin (40-50%), a filler (35-50%),optionally a plasticizer (5%), and small amounts of lubricant andpigments. The powder can be cured in a mold at 120°-185° C. under apressure of 2,000 pounds per square inch or more. In the standardone-stage process for the manufacture of resin for laminated materialsand for lacquers, 1.0 mole of phenol and 1.5 moles of formaldehyde(usually 40% solution) and a basic catalyst are heated. After a fewhours, the mixture settles into two layers. After removal of the upperwater layer, more water is eliminated by heating in a vacuum. Then theresulting syrup is poured into shallow pans to cool, producing a type Bresin, soluble in alcohol. Molding powders are usually made by thetwo-stage process.

Useful laminated products can be made from such resins and paper,canvas, fibers, and wood.

11. Preparation of Novolak Resins

Although this invention is primarily directed towards alkalinephenol-formaldehyde resins that are thermosetting, it is also possibleto make novolak (thermoplastic) resins using the extracts of thisinvention under certain conditions. Where the alkaline extraction methodis used, alkaline salts generally remain in the concentrated extract,and therefore, such extracts are logically most easily used in preparingan alkaline catalyst phenol-aldehyde resin. However, it is chemicallypossible to neutralize the alkali and use the extract in reaction withaldehyde under acid conditions, to produce a novolak-type resin. Thiscan be accomplished particularly easily where ammonium hydroxide aqueoussolution is used as the extracting agent. In this instance, the ammoniaremaining in the extract can be removed by simply evaporating the waterusing any conventional process, so that the dry powder remaining isessentially neutral or only slightly alkaline. Even where the extract isconcentrated with some water remaining, removal of the water byevaporation will tend to remove a great deal of the ammonium hydroxide,since ammonium hydroxide is more volatile than water. Thus, an alkalineextract prepared using ammonium hydroxide aqueous solution easily can beused in the preparation of novolak resins, using conventional catalystsand proportions of extract and aldehyde for the production of this typeof resin. The proportions of phenol to the extract of this invention canbe the same as those disclosed for the preparation of alkaline catalystresins and the manner of preparing the resins can be essentially thesame as that disclosed in the examples and specification of thisinvention, with appropriate changes of alkalinity/acidity,aldehyde:phenol: extract ratio, temperature, etc., applied mutatismutandis to the production of novolak resins.

Since an extract prepared using the sulfite pulping method is notstrongly alkaline, such extracts also would be useful in the preparationof novolak resins in the same manner as alkaline resins preparedaccording to this invention which either have been neutralized or whichhave had the ammonium hydroxide removed.

It also would be possible to produce a novolak or seminovolak resin byreplacing part of the extract with a substitutued phenol containing onlyone free active site, for example 2,4-xylenol. Replacement of part ofthe extract with a phenol having two free active sites, such as ortho-or para-cresol, can produce a partially or slowly curable resin.

Additionally, a novolak resin can be made by replacement of the extractwith a phenol having three free active sites, provided that the amountof aldehyde used is substantially reduced.

I claim:
 1. A phenol-aldehyde consisting essentially of the reactionproduct of up to 4.0 parts by weight of a conventional thermosettingphenol-aldehyde resin precondensate having a viscosity of from 20 to 800cps at 25° C., and 1.0 part by weight of an alkali organic extract ofpecan piths, said extract containing phenolic compounds and at least 2%by weight of crude protein, based on weight of said extract, wherein themixture is polymerized in an aqueous alkaline system at a temperature offrom 30° C. to reflux, until a viscosity of from 20 to 3,000 cps at 25°C. is reached.
 2. The resin composition of claim 1 wherein thepolymerization is carried out in an aqueous alkaline system containingfrom 2 to 20% alkali concentration by weight.
 3. A phenol-aldehyde resincomposition consisting of essentially of the polymerization productof(a) one part by weight of an alkali organic extract of pecan piths,said extract containing phenolic compounds and at least 2% by weight ofcrude protein, based on weight of said extract, and (b) 0.1 to 1.6 partsby weight, based on weight of said extract, of an aldehyde.
 4. Aphenol-aldehyde type resin composition consisting essentially of 1.0parts by weight of the resin of claim 3 in physical mixture with up to4.0 parts by weight of a conventional thermosetting phenol-aldehyderesin.
 5. A phenol-aldehyde resin consisting essentially of from 1.0part by weight of the resin of claim 3 which has been polymerized to aprecondensate having a viscosity of not more than 800 cps at 25° C., andwhich has been physically mixed with up to 4.0 parts by weight of aconventional thermosetting phenol-aldehyde resin precondensate having aviscosity of from 20 to 800 cps at 25° C., and wherein the mixture isfurther polymerized to form a copolymer resin.
 6. The resin of claim 3in which up to about 80% by weight of the extract composition isreplaced by a phenol having at least 2 free active sites.
 7. The resinof claim 3 wherein the aldehyde is selected from at least one of thegroup consisting of formaldehyde, para-formaldehyde, trioxane,hexamethylene tetramine, furfuraldehyde, and formalin.
 8. Thecomposition of claim 6 wherein the phenol is selected from at least oneof the group consisting of phenol, cresol, xylenol, and resorcinol, allhaving at least 2 free active sites.
 9. The composition of claim 6wherein polymerization is conducted at a temperature of from about 30°to about 75° C., until addition is completed, and then continued at atemperature of from about 55° C. to reflux until condensation iscompleted.
 10. The resin of claim 6 wherein not more than 60% of thealkaline extract is replaced by phenol.
 11. The resin of claim 6 inwhich the alkali concentration during polymerization is adjusted to from3 to 15% by weight.
 12. A phenol-aldehyde cellulosic materialimpregnation resin consisting essentially of the resin of claim 3,polymerized to a viscosity of from 20 to 1,500 cps at 25° C.
 13. Thephenol-aldehyde resin composition of claim 3 wherein the alkali of saidorganic extract is a member selected from the group consisting of sodiumand potassium.
 14. The phenol-aldehyde resin composition of claim 3wherein the alkali of said organic extract is ammonium.
 15. Thephenol-aldehyde resin composition of claim 3 wherein said extractcontains at least 5% by weight of crude protein.
 16. The phenol-aldehyderesin composition of claim 3 wherein the polymerization of said organicextract and aldehyde is carried out in an aqueous alkaline system. 17.The phenol-aldehyde resin composition of claim 3 wherein thepolymerization of said organic extract and aldehyde is carried out in anaqueous acid system.
 18. The phenol-aldehyde resin composition of claim3 wherein the polymerization is carried out in an aqueous alkalinesystem at a temperature of 30° C. to reflux, until a viscosity of from20 to 1,500 cps at 25° C. is reached.
 19. The phenol-aldehyde resincomposition of claim 3 wherein the polymerization is carried out in anaqueous alkaline system at a temperature of 30° C. to reflux, until aviscosity of from 250 to 1,500 cps at 25° C. is reached.
 20. The resincomposition of claim 3 wherein 20 to 80% by weight of said extract isreplaced by phenolic compounds.